In this Aug. 14, 2012 file photo, President Obama is greeted on stage by a thumbs-up from Mike Dufel of Cedar Falls, Iowa, during a campaign event at Waterloo Center for the Arts in Waterloo, Iowa. (AP Photo/Carolyn Kaster, File)

In this April 27, 2012 file photo, President Obama and first lady Michelle Obama are saluted by soldiers as they arrive at the Fort Stewart Army post in Fort Stewart, Ga. (AP Photo/David Goldman, File)

Photo: David Goldman, Associated Press

In this April 27, 2012 file photo, President Obama and first lady...

In this April 27, 2012 file photo, President Obama and first lady... Photo-3695619.51928 - SFGate

In this July 14, 2012 file photo, President Obama holds a campaign... Photo-3695593.51928 - SFGate

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In this April 23, 2012 file photo, President Obama strikes the Heisman pose after he awarded the Commander-in-Chief Trophy to the Air Force Academy football team in the East Room of the White House in Washington. (AP Photo/Charles Dharapak, File)